tHpodomya phillipsi Gray. \ 91 



In the light of the ample material collected by Mr. Nelson, 

 the species may be redefined as follows : 



Dipodomys phillipsi Gray. 



Dipodomys phillipii Gray, Ann. and Mag. Nat. Hist., vii, 1841, 522. (Name 

 spelled phillipii by typographical error and corrected to D. 

 phillipsii by same author a few months later. Am. Journ. 

 Sci., XLII, 1842, 335.) 



^f(l^rocolus haUicus A. Wagner, Wiegmann's Archiv fiir Naturgeschichte, 

 1846, 172-177 (from 'Mexico'). 



Dipodomys phillipsn Audubon and Bachman, Quadrupeds of North Amer- 

 ica, vol. in, 1854, plate (colored) cxxx (of Gray's type speci- 

 men), and pp. 137-140 in part. 

 NOTE. The D. phillipsi of subsequent authors is composite and does 



not include this species at all. 



Type Locality. The Valley of Mexico, Mexico. 



General Characters. Tip of tail white; size, smallest of the 

 species having this peculiarity (about equaling D. merriami, but 

 tail longer) ; coloration very dark, resembling D. californicus. 



Measurements. Average of 23 adult specimens from Tlalpam and Ajusco, 

 at the south end of the Valley of Mexico (measured in the flesh) : Total 

 length, 270 mm. ; tail vertebrae, 168 ; hind foot, 41. 



Color. Upper parts sepia-brown, more or less suffused with 

 ochraceous, and everywhere conspicuously mixed w T ith black- 

 tipped hairs ; thigh patches large, becoming dusky, and forming 

 a large black patch behind and on the sides of lower leg and 

 ankle, reaching upper surface of heel; crescents at base of 

 whiskers large, nearly black, and meeting across nose ; eyelids 

 black ; supraorbital spot obscured ; upper and lower tail stripes 

 black, meeting along distal third, and succeeded by a short 

 brush of pure white, usually measuring only 10 to 15 mm., thus 

 being decidedly shorter than in any other white-tipped species. 



Cranial Characters. Skull slightly larger than D. merriami, 

 but not so large as D. californicus. Viewed from above, the 

 post-rostral portion of the cranium is subquadrate in shape, owing 

 to the gi*eat breadth across the orbital bridges of the maxillaries, 

 and the relatively slight development of the mastoids. The 

 least interobital breadth of the frontals is greater than in any 

 other species of the genus, equaling or exceeding the distance 

 from the foramen magnum to the premolar, and considerably 

 exceeding the length of the nasal bones. The tympanic capsule 



13 Bior,. Soc. WASH., Vor,. VIII, 1893. 



